Sensitive and reproducible platforms have been developed for detection, isolation, and enrichment of circulating tumor cells (CTCs)—rare cells that enter the blood from solid tumors, including those of the breast, prostate, lung, pancreas, and colon. These might be used as biomarkers in diagnosis or determination of prognosis. CTCs are no longer simply detected and quantified—they are now used in ex vivo studies of anti-cancer agents and early detection. We review what we have recently learned about CTCs from pancreatic tumors, describing advances in their isolation and analysis, and challenges to their clinical utility.